The present invention relates to a centralized control system for open and spinning machines and, more particularly, to a control system for use in open and spinning machine of the type which is fully automated.
Open end spinning machines are presently in wide use to overcome various drawbacks which are inherent in the traditional spinning machine, providing outstandingly enhanced efficiency in the production of spun yarns. Numerous types of such open end spinning machines are being proposed in the art of textile fabrics production.
The open and spinning machine consists of a great number of, usually hundreds of spinning units which are arranged in a row on a common machine frame. Each of the spinning units comprises a combing roller having a peripheral surface formed with a number of projections which have, for example, saw-tooth configurations. A sliver of fibers to be spun is continuously fed by means of a sliver feed roller onto the toothed peripheral surface of the combing roller so that the fibers forming the sliver engage the projections of the combing roller. The combing roller is driven to rotate abouts its axis for opening up the sliver into fibers which are separate from each other. The separate fibers are then "doffed" or taken from the toothed peripheral surface of the combing roller and are forced into a rotary spinning chamber by a jet stream of air. The spinning chamber is driven to rotate about its axis so that the fibers are deposited onto an annular fiber-collecting area which is formed along the circumference of the spinning chamber. A yarn is thus continuously formed at the fiber-collecting area of the spinning chamber and is continuously withdrawn from the spinning chamber through a discharge opening which is located in line with the axis of rotation of the spinning chamber. The finished yarn is drawn away from this discharge opening by means of a set of draw-off rollers and is thereafter wound on a take-up roller into a suitable yarn package which may be in the form of a cheese as is customary in the art.
Each of the spinning units is provided with a sensor for detecting yarn breakage condition which may be invited in the spinning unit during operation. The yarn breakage sensor produces a signal in response to yarn breakage which is invited in the associated spinning unit so as to temporarily stop the particular spinning unit. The operational members of the spinning unit are then driven selectively and sequentially, whereupon servicing or repairing operation is conducted on the particular spinning unit for rejoining the broken yarn in the unit. During the servicing operation, the draw-off rollers and the take-up roller are first driven in reverse directions so that the yarn hanging down from the yarn package is fed back until the cut end of the yarn reaches the fiber-collecting area in the spinning chamber. The sliver feed roller, the combing roller and the rotary spinning chamber are then re-started so that a yarn is produced anew at the fiber-collecting area of the spinning chamber. The newly spun yarn is joined to the cut end of the previously spun yarn in the spinning chamber. When the yarn is thus re-joined, the draw-off rollers and the take-up roller are driven in usual directions for continuously withdrawing the yarn from the spinning chamber.
When the spinning unit is operating under proper conditions, the rotary members, especially the combing roller and the spinning chamber, of the unit are driven at extremely high speeds. For instance, the combing roller is driven at about 6,000 rpm and the spinning chamber driven at about 30,000 rpm. If such high speeds are maintained also during the servicing operation, almost prohibitorily exact control would be indispensable over the timings at which the individual rotary members of the spinning unit are sequentially initiated into action to proceed with the servicing operation. It is, therefore, a usual practice to have the rotary members of the spinning unit driven at speeds which are lower than usual operating speeds of the members so as to provide ample allowance between the timings at which the rotary members lending themselves to the yarn-rejoining operation are actuated.
The spinning units constituting a single open end spinning machine are in most cases driven by a common driving source through gearings or other suitable power transmission mechanisms which are respectively associated with the spinning units. When yarn breakage happens to take place in one of the spinning units, then the particular spinning unit is temporarily disconnected from the driving source in response to the signal from the yarn breakage sensor provided in the spinning unit and is connected for a second time to the driving source so as to receive the servicing operation. Since, in this instance, all the spinning units are driven by the same driving source and since the spinning unit in the yarn breakage condition must be driven at a reduced speed during the servicing operation as above noted, even the spinning units operating in proper conditions must be slowed down while the unit involving the yarn breakage condition in being serviced to restore the proper operational conditions. This apparently results in a considerable loss in the production efficiency of the machine as a whole and is accordingly unacceptable in today's textile fabrics production industry in which speeding up the production rate is one of the imperative requirements. Research and development efforts are thus being paid in various quarters of the industry in quest of advanced open and spinning machines which are cleared of the drawbacks above pointed out.
One of such advanced versions of open end spinning machines comprises a number of drive units each of which is exclusively associated with each of the spinning units constituitng the machine. The drive unit proper to one spinning unit operates independently of the drive units of the remaining spinning units and, thus, only the spinning units involving the yarn breakage condition can be slowed down during the servicing operation with the remaining spinning units kept driven at their usual operating speeds. If, in this instance, each of the drive units is provided with a control system which is proper to the particular unit, then it becomes necessary to have a great number of separate control systems incorporated in the spinning machine for controlling the hundreds of spinning units and the associated driving arrangements. Problems will then arise because of a tremendously increased cost of the spinning machine and a vast amount of human labor that will be required for the maintenance and servicing of the control systems. The present invention contemplates provision of an improved control system which is free from any of the drawbacks thus far pointed out.
It is, accordingly, an important object of the present invention to provide a centralized control system which is capable of controlling a great number of spinning units with enhanced efficiency.
It is another important object of the present invention to provide a centralized control system which is adapted to simultaneously control the spinning units in common modes of operation when the spinning units are operating under proper conditions and to yet control a limited number of spinning units independently of the remaining units when yarn breakage conditions are invited in the limited number of units.
It is, thus, still another important object of the present invention to provide a centralized control system which is predominant over the operations of all of the spinning units and which is nevertheless capable of functioning as if it were proper to one of or a limited number of spinning units when the unit or units are in the yarn breakage conditions.
It is still further important object of the present invention to provide a centralized control system wherein each spinning operation including servicing of yarn breakage is controlled and supervised by control commands from a group and an individual control units each including a plurality of sequentially operated logical elements and a braking unit, whereby the reliability of yarn rejoining operation can be extremely improved.
In accordance with the present invention, these and other objects are accomplished in a centralized control system comprising a group control unit essentially consisting of a first variable frequency power supply connected to a plurality of spinning units, a first spinning control means composed of a plurality of sequentially operated logical elements connected in series, the first spinning control means producing from the final-stage logical elements a command which is fed to the first power supply so as to increase the operational frequency of the power supply, the first spinning control means further producing from the respective logical elements parallel outputs each of which is fed to the spinning units so as to control the spinning operation thereof, an individual control unit comprising a second variable frequency power supply and a second spinning control means each of which constituent is the same as the first variable frequency power supply and the first spinning control means, the individual control unit further comprising a synchronizing detector producing an output when the operational frequency of the second power supply becomes equal to the operational frequency of the first power supply, a switching circuit for changing the control of the spinning unit in which the repair of yarn breakage has been effected from the individual control unit to the group control unit in response to the output of the synchronizing detector, and the plurality of spinning units each of which comprises a spinning mechanism for rendering sliver of fibers spun to form a spun yarn and taking up the spun yarn onto a take-up means, the spinning mechanism including a yarn breakage sensor provided in the stream of spun yarn, a driving means for driving the spinning mechanism including a plurality of driving motors, controlled by the output from the first or second variable frequency power supply, wherein there occurs no yarn breakage in any one of the plurality of spinning units, the spinning units are all controlled by the group control unit, while when there occurs yarn breakage in any one of the plurality of spinning units, only the spinning unit in which yarn breakage is invited is shifted from the group control unit to the control of the individual control unit, and then after yarn breakage invited in the spinning unit is repaired, the spinning unit is for a second time shifted to the control of the group control unit.